1. Field of the Invention
This invention relates to a valve system for a hydraulic, adjustable vibration damper with a piston fastened to a piston rod, which piston divides a work cylinder into two work chambers filled with damping fluid, whereby at least partly to control the damping force, there is a valve system with at least one electromagnetically activated valve, respectively consisting of a housing, a coil, an armature and a nonreturn body.
2. Background Information
The prior art includes valve systems for hydraulic, adjustable vibration dampers (e.g. German Laid Open Patent Appln. No. 39 36 453), on which there is a valve system consisting of at least one valve to control the damping force, and whereby, to achieve a secure electrical connection, after the coil body is inserted into the nonreturn body, the individual magnet covers are encased in plastic.
The contact points between the nonreturn body and the valve casing contribute to the possibility of leakage of undesirable components into the structure and the electromagnetic assembly into the entire valve assembly. A surface treatment, e.g. galvanizing, means on one hand a reduction of the quality of fit, since the zinc coating is uneven, and on the other hand a loss of magnetic force, since zinc does not have ferromagnetic characteristics. Therefore, even with thin coatings which are resistant to corrosion, care must be taken that the contact points do not attract moisture. Any corrosion which may occur at this gap can result in the failure of the entire valve.
Encasing the valve body, after it is introduced into the nonreturn body, by spraying it over with an appropriate plastic does not achieve the required tightness. Even with a coil complex and a nonreturn body which are manufactured separately and then connected to one another by means of adhesive, the proper seal cannot always be guaranteed, since the coil becomes extremely hot during operation, and hairline cracks, at the very least, can be expected on account of the stresses between the different types of materials.